Marfa climate

Marfa Frost Dates and Growing Season

NOAA 1991-2020 normals for Marfa 3W, 4.9 km from Marfa, elevation 4790 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Marfa 3W. A median date has an even chance of a later freeze in spring, or an earlier one in fall.

The last spring freeze typically comes around April 14 and the first fall freeze around October 27, a growing season of about 196 days.

Median at 36°F
last April 26, first October 19
Median at 32°F
last April 14, first October 27
Median at 28°F
last April 2, first November 7

Last freeze in spring

The chance of a later freeze than the date shown. At 10 percent, one spring in ten still freezes after the date; planting after the 10 percent date for 32°F is the cautious choice.

Threshold10%20%30%40%50%60%70%80%90%
36°FMay 9May 4May 1Apr 29Apr 26Apr 22Apr 19Apr 14Apr 9
32°FMay 1Apr 26Apr 21Apr 18Apr 14Apr 11Apr 7Apr 4Mar 30
28°FApr 21Apr 14Apr 9Apr 5Apr 2Mar 30Mar 23Mar 17Mar 12
24°FApr 6Mar 31Mar 24Mar 18Mar 14Mar 10Mar 7Mar 3Feb 26
20°FMar 20Mar 12Mar 8Mar 3Feb 28Feb 24Feb 19Feb 14Feb 8
16°FMar 7Feb 28Feb 24Feb 17Feb 10Feb 5Jan 31Jan 25Jan 15

First freeze in fall

The chance of an earlier freeze than the date shown. At 10 percent, one fall in ten freezes before the date.

Threshold10%20%30%40%50%60%70%80%90%
36°FOct 4Oct 8Oct 13Oct 16Oct 19Oct 21Oct 25Oct 29Nov 3
32°FOct 13Oct 18Oct 21Oct 24Oct 27Nov 1Nov 4Nov 7Nov 13
28°FOct 20Oct 25Oct 29Nov 3Nov 7Nov 10Nov 13Nov 16Nov 22
24°FOct 29Nov 6Nov 11Nov 14Nov 17Nov 20Nov 24Nov 28Dec 2
20°FNov 11Nov 17Nov 22Nov 26Nov 29Dec 2Dec 5Dec 9Dec 16
16°FNov 22Nov 30Dec 3Dec 7Dec 11Dec 16Dec 21Dec 26Jan 2

Growing season length

Days between the last spring and first fall freeze at each threshold, with the chance of a season at least that long.

Threshold10%20%30%40%50%60%70%80%90%
36°F198189184180175171167163156
32°F217210204200196191186181172
28°F242234227222216211206199191
24°F270262256251245240234226216
20°F300288283277272267262255244
16°F335324315308302295288280270

How often it gets that cold

The share of years with at least one night at or below each temperature.

36°F or colder
100% of years
32°F or colder
100% of years
28°F or colder
100% of years
24°F or colder
100% of years
20°F or colder
100% of years
16°F or colder
100% of years

Degree days

A degree day is one degree of the daily mean temperature beyond a base, for one day. Heating degree days count cold (the fuel a house burns), cooling degree days heat, growing degree days the warmth a crop needs; each crop has its own base.

Heating degree days, base 65°F
3,228
Cooling degree days, base 65°F
1,183
Growing degree days, base 40°F
7,248
Growing degree days, base 45°F
5,663
Growing degree days, base 50°F
4,263
Growing degree days, base 55°F
3,052
Growing degree days, base 60°F
2,019

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January71607
February550026
March4051124
April17816299
May36130560
June1303753
July0315780
August0273738
September30129550
October17415316
November437198
December701014

What this means

NOAA computes these from the daily lows at the station over 1991-2020, fitting the dates of each year's last and first freeze to a distribution, so a date can be stated at any level of risk. 36°F is a frost risk for tender plants on a clear, calm night, since the ground cools below the air above it; 32°F is a freeze; 28°F is a hard freeze that kills most annuals.

The station is 4.9 km from Marfa. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00415596 (Marfa 3W). Public domain.